Medical procedures for draining fluids from a patient require care to prevent infection, and may require control of the drainage rate and/or control of pressure of the fluid within the patient. Devices to prevent infection and to control fluid flow rate and pressure are especially important in carrying out procedures for draining excess cerebro-spinal fluid (CSF) from the ventricles of a patient's brain, since if the pressure of the CSF is either too high or too low, the result may be permanent injury or death.
In a typical CSF drainage system, a drip chamber is interposed between a drainage tube extending from a patient and a collection vessel in order to provide a break in the flow path of the liquid and thereby prevent backward movement of microbes which may be present. If the chamber overflows, there is a danger that a path will be provided for movement to the patient of microbes which may be present.
These prior art devices typically include a vent device at the top of the drip chamber to prevent a buildup of pressure. The vent may be provided with a filter to prevent contamination of the system; however, there is danger that pressure will increase within the drip chamber if the filter becomes wet, which may result from fluid overflow or fluid which splashes within the drip chamber.